Harper has also spoken to U.S. President Barack Obama and British Prime Minister David Cameron, but has not yet had a conversation with Russian President Vladimir Putin.
Speaking at a mining conference in Toronto Monday afternoon, Harper talked briefly about Ukraine before sitting down for an interview with a conference spokesperson about the economy.
"Canada has suspended our engagement in preparations for the G8 summit planned in Sochi. We have also recalled our ambassador to Russia. [We] cancelled any government representation at the paralympic games and I've instructed officials to review all planned bilateral interaction with Russia," Harper announced.
Harper's cabinet held an emergency cabinet meeting Saturday and Foreign Affairs Minister John Baird held a news conference Sunday following the news that Putin has assembled Russian military forces in Crimea, which is part of Ukraine.
Harper consults with NDP's Tom Mulcair
Harper also called Opposition Leader Tom Mulcair about his decision to recall Canada's ambassador and pull out of the G8 summit. On Sunday, speaking in Toronto, Mulcair described his conversation with the prime minister.
"He called me and gave me a very detailed briefing on the current situation. We're of one mind. The world community has to come together and use whatever diplomatic tools at our disposal to show Russia that this is not an acceptable form of behaviour."
Baird, who had just returned from a visit to Ukraine, told reporters Sunday he had met with members of the interim government while he was in Kyiv on Friday.
"What we want to do is de-escalate this situation, and we want Putin and Russia to back down from their actions. Obviously we'll take this one step at a time and see where it goes. We are in close contact with friends and allies and will continue to do so," Baird said.
Jeff Sahadeo, the director of European, Russian and Eurasian studies at Carleton University in Ottawa, said in a phone interview, "Canada's role in the end, if it were to be productive, might be to act as a go-between with the U.S. and the European Union to make sure that all the Western powers are on the same page, because that's a problem now."
The EU and the U.S. have different interests, he explained. Europe is heavily reliant on Russia for natural gas exports whereas the interests of the U.S. are "geo-political." He suggested Canada could use the experience gained in its free trade negotiations with the EU and act as an intermediary with the U.S.
Sahadeo also said that Putin is probably happy with the "stalemate" situation he has precipitated by surrounding military assets in Crimea, with the Western powers anxious not to provoke anything.
"Where I see the danger is in unpredictable events. Say, a shot fired at a base, somebody retaliates, more shots are fired, all of a sudden all these western Ukrainians decide 'We're going to fight for the motherland.'"
Vadym Prysaitko, the Unkrainian ambassador in Canada, told CBC News his country is pleased the G8 nations have condemned Russia's actions. He acknowledged Ukraine has mobilized its 100,000 troops, and that citizens are signing up to enlist in the reserves.
"We don't want anybody to get hurt, we don't want to spark any war," he said.